This invention relates to a process for preparing polyols by reacting an active hydrogen initiator with an epoxide using a heterogeneous catalyst.
Polyols are useful as solvents, surfactants, metal cutting oils, hydraulic fluids and as chemical intermediates in the manufacture of polyurethanes.
Polyols made from asymmetrical epoxides contain predominantly secondary terminal hydroxyl moieties when catalyzed by base. Polyols having primary hydroxyl moieties are more desired but are not available via base-catalyzed alkoxylation with asymmetrical epoxides. They are generally formed by end capping the polyol with ethylene oxide. It would be desirable to have a process which produces a larger amount of polyols having primary terminal hydroxyl moieties without the use of ethylene oxide.
In addition, asymmetrical epoxides can rearrange to produce terminal unsaturation under certain circumstances. This terminal unsaturation limits molecular weight and functionality attainable in the polyol and is detrimental when the polyol reacts, particularly in reactions with isocyanates to form polyurethanes. Therefore, it would be desirable to have a process which produces a polyol product having a low level of terminal unsaturation.
Active hydrogen initiators vary in acidity, depending on their elemental composition and the arrangement of the elements in the active hydrogen initiator. Heretofore, homogeneous base catalyzed polymerization processes have used catalysts which have not been effective with the less acidic active hydrogen initiators such as tertiary alcohols. It would be desirable to have a process which uses a catalyst which is effective with the less acidic active hydrogen initiators which conventional processes cannot effectively utilize.